Black cohosh for menopausal symptoms

Table of Contents (click to jump to sections)

What is black cohosh?
What are common black cohosh preparations?
What clinical studies have been done?
How does black cohosh work?
What is the regulatory status of black cohosh in the USA?
Can black cohosh be harmful?
Who should not take black cohosh?

Black cohosh (known as both Actaea racemosa and Cimicifuga racemosa), a member of the buttercup family, is a perennial plant that is native to North America. Other common names include black snakeroot, bugbane, bugwort, rattleroot, rattletop, rattleweed, and macrotys. Insects avoid it, which accounts for some of these common names.

Preparations of black cohosh are made from its roots and rhizomes (underground stems). One commercial standardized black cohosh preparation is Remifemin®*, which contains black cohosh extract equivalent to 20 mg of root per tablet. The manufacturer changed the formulation of this preparation from a solution (root extracted with ethanol, 60% by volume) to tablets (root extracted with isopropyl alcohol, 40% by volume), complicating the comparison of research results. Other preparations of black cohosh have been less well studied than Remifemin. Extracts of black cohosh are standardized to 26-deoxyactein content , a member of a group of chemicals known as saponins. Commercially available preparations of black cohosh usually contain 1 mg of total triterpene saponins (expressed as 26-deoxyactein) in each 20-mg dose of extract.

Black cohosh is used primarily for hot flashes and other menopausal symptoms. A number of studies using various designs have been conducted to determine whether black cohosh affects menopausal symptoms. Few studies were placebo controlled, and most assessed symptoms by using the Kupperman index-a scale that combines measures of hot flashes, insomnia, and depression but not vaginal dryness. Those with the best study designs are described below.

A randomized, double-blind, placebo-controlled trial was done in breast cancer survivors because most of these women experience hot flashes and A lot of use complementary or alternative remedies . The women were over age 18 and had completed breast cancer treatment at least 2 months before the trial; 85 women (69 of whom completed the trial) took one tablet of placebo or 40 mg/day of black cohosh (as 20 mg twice daily) for 2 months to determine the effect on hot flashes, excessive sweating, palpitations, headaches, poor sleep, depression, and irritability [J.S. Jacobson, Columbia University, written communication, 2002]. Fifty-nine subjects were using tamoxifen (an antiestrogen treatment for breast cancer); tamoxifen users were distributed almost equally between the treatment and control groups. The frequency and intensity of hot flashes decreased in both groups, with no statistical difference between the groups; excessive sweating decreased significantly more in the treatment group than the placebo group. Other symptoms improved equally in both groups, and scores on a health and well-being scale did not change significantly in either group.

A 24-week study in 60 women who had undergone hysterectomy but retained at least one ovary compared the effects of 8 mg/day of a black cohosh extract (as four 2-mg tablets daily; isopropanol extract version of Remifemin) with three estrogen regimens: estriol (1 mg/day), conjugated estrogens (1.25 mg/day), and estrogen-progestin therapy (one daily Trisequens® tablet containing 2 mg estradiol and 1 mg norethisterone acetate). In all groups a modified Kupperman index measuring additional physical symptoms was significantly lower 4, 8, 12, and 24 weeks after treatment began. Black cohosh decreased symptoms similarly to the other treatments, but this study was not placebo controlled.

How black cohosh works is not known. The possibility that black cohosh exhibits estrogenic activity has been studied but the evidence is contradictory .

A compound recently identified in black cohosh—fukinolic acid—was shown to have estrogenic activity in vitro . Other active compounds appear to include triterpene glycosides (including actein and cimicifugoside), resins (including cimicifugin), and caffeic and isoferulic acids .

In the USA, black cohosh is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. manufacturars do not have to provide the United States of America Food and Drug Administration with evidence that dietary supplements are effective or safe before marketing. Because dietary supplements are not always tested for manufacturing consistency, the composition may vary considerably from lot to lot.

Black cohosh can cause stomach discomfort and headaches. Clinical trials comparing estrogens with black cohosh preparations have shown a low incidence of adverse effects associated with black cohosh; headaches, gastric complaints, heaviness in the legs, and weight problems were the main adverse effects noted .

Black cohosh usually has not been used for long periods, and published studies have followed women for only 6 months or less. Recently, a large study that followed postmenopausal women taking combined estrogen and progestin for an average of 5.2 years showed a small but significant increase in the risk of certain diseases, demonstrating the importance of long-term studies in revealing risks that may not be apparent in shorter studies. If black cohosh is estrogenic, long-term use may adversely affect uterine or breast tissue. No studies have been published on long-term safety in humans, mainly regarding abnormal stimulation of cells in the endometrium or breast.

There is a case report of neurological complications in a postterm baby after labor induction with a mixture of black cohosh and blue cohosh (Caullophylum thalictroides) during a home birth.